Development of leptin resistance in rat soleus muscle in response to high-fat diets

2000 ◽  
Vol 279 (6) ◽  
pp. E1374-E1382 ◽  
Author(s):  
Greg R. Steinberg ◽  
David J. Dyck
Keyword(s):  
Skeletal Muscle ◽  
Lipid Metabolism ◽  
Soleus Muscle ◽  
Leptin Resistance ◽  
Safflower Oil ◽  
High Fat ◽  
Muscle Lipid ◽  
High Fat Diets ◽  
Rat Soleus Muscle ◽  
Fat Diets

Direct evidence for leptin resistance in peripheral tissues such as skeletal muscle does not exist. Therefore, we investigated the effects of different high-fat diets on lipid metabolism in isolated rat soleus muscle and specifically explored whether leptin's stimulatory effects on muscle lipid metabolism would be reduced after exposure to high-fat diets. Control (Cont, 12% kcal fat) and high-fat [60% kcal safflower oil (n-6) (HF-Saff); 48% kcal safflower oil plus 12% fish oil (n-3)] diets were fed to rats for 4 wk. After the dietary treatments, muscle lipid turnover and oxidation in the presence and absence of leptin was measured using pulse-chase procedures in incubated resting soleus muscle. In the absence of leptin, phospholipid, diacylglycerol, and triacylglycerol (TG) turnover were unaffected by the high-fat diets, but exogenous palmitate oxidation was significantly increased in the HF-Saff group. In Cont rats, leptin increased exogenous palmitate oxidation (21.4 ± 5.7 vs. 11.9 ± 1.61 nmol/g, P = 0.019) and TG breakdown (39.8 ± 5.6 vs. 27.0 ± 5.2 nmol/g, P = 0.043) and decreased TG esterification (132.5 ± 14.6 vs. 177.7 ± 29.6 nmol/g, P = 0.043). However, in both high-fat groups, the stimulatory effect of leptin on muscle lipid oxidation and hydrolysis was eliminated. Partial substitution of fish oil resulted only in the restoration of leptin's inhibition of TG esterification. Thus we hypothesize that, during the development of obesity, skeletal muscle becomes resistant to the effects of leptin, resulting in the accumulation of intramuscular TG. This may be an important initiating step in the development of insulin resistance common in obesity.

Endurance training partially reverses dietary-induced leptin resistance in rodent skeletal muscle

2004 ◽  
Vol 286 (1) ◽  
pp. E57-E63 ◽  
Author(s):  
Gregory R. Steinberg ◽  
Angela C. Smith ◽  
Sam Wormald ◽  
Patrick Malenfant ◽  
Cheryl Collier ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Mrna Expression ◽  
Endurance Training ◽  
Exercise Intervention ◽  
Leptin Resistance ◽  
Cytokine Signaling ◽  
High Fat ◽  
High Fat Diets ◽  
Fat Diets ◽  
Socs3 Mrna

Leptin acutely stimulates skeletal muscle fatty acid (FA) metabolism in lean rodents and humans. This stimulatory effect is eliminated following the feeding of high-fat diets in rodents as well as in obese humans. The mechanism(s) responsible for the development of skeletal muscle leptin resistance is unknown; however, a role for increased suppressor of cytokine signaling-3 (SOCS3) inhibition of the leptin receptor has been demonstrated in other rodent tissues. Furthermore, whether exercise intervention is an effective strategy to prevent or attenuate the development of skeletal muscle leptin resistance has not been investigated. Toward this end, 48 Sprague-Dawley rats (175-190 g; ∼2-3 mo of age) were fed control or high-fat (60% kcal) diets for 4 wk and either remained sedentary or were treadmill trained. In control diet-fed animals that remained sedentary (CS) or were endurance trained (CT), leptin stimulated FA oxidation (CS +32 ± 15%, CT +30 ± 17%; P < 0.05), suppressed triacylglycerol (TAG) esterification (CS -17 ± 7%, CT -24 ± 8%; P < 0.05), and reduced the esterification-to-oxidation ratio (CS -19 ± 13%, CT -29 ± 10%; P < 0.001) in soleus muscle. High-fat feeding induced leptin resistance in the soleus of sedentary rats (FS), whereas endurance exercise training (FT) restored the ability of leptin to suppress TAG esterification (-19 ± 9%, P = 0.038). Training did not completely restore the ability of leptin to stimulate FA oxidation. High-fat diets stimulated SOCS3 mRNA expression irrespective of training status (FS +451 ± 120%, P = 0.024; FT +381 ± 141%, P = 0.023). Thus the development of skeletal muscle leptin resistance appears to involve an increase in SOCS3 mRNA expression. Endurance training was generally effective in preventing the development of leptin resistance, although this did not appear to require a decrease in SOCS3 expression. Future studies should examine changes in the actual protein content of SOCS3 in muscle and establish whether aerobic exercise is also effective in treating leptin resistance in humans.

Adiponectin Resistance Develops in Rat Soleus Muscle in Response to High-Fat Diets

2006 ◽  
Vol 38 (Suppl 1) ◽  
pp. S15
Author(s):  
Kerry L. Mullen ◽  
Kathryn A. Junkin ◽  
Angela C. Smith ◽  
David J. Dyck
Keyword(s):  
Soleus Muscle ◽  
High Fat ◽  
High Fat Diets ◽  
Rat Soleus Muscle ◽  
Fat Diets ◽  
Adiponectin Resistance

Influence of high-fat diet from differential dietary sources on bone mineral density, bone strength, and bone fatty acid composition in rats

2010 ◽  
Vol 35 (5) ◽  
pp. 598-606 ◽  
Author(s):  
Beatrice Y. Lau ◽  
Val Andrew Fajardo ◽  
Lauren McMeekin ◽  
Sandra M. Sacco ◽  
Wendy E. Ward ◽  
...  
Keyword(s):  
Bone Mineral Density ◽  
Fatty Acids ◽  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Acid Composition ◽  
Safflower Oil ◽  
High Fat ◽  
Mineral Density ◽  
High Fat Diets ◽  
Fat Diets

Previous studies have suggested that high-fat diets adversely affect bone development. However, these studies included other dietary manipulations, including low calcium, folic acid, and fibre, and (or) high sucrose or cholesterol, and did not directly compare several common sources of dietary fat. Thus, the overall objective of this study was to investigate the effect of high-fat diets that differ in fat quality, representing diets high in saturated fatty acids (SFA), n-3 polyunsaturated fatty acids (PUFA), or n-6 PUFA, on femur bone mineral density (BMD), strength, and fatty acid composition. Forty-day-old male Sprague–Dawley rats were maintained for 65 days on high-fat diets (20% by weight), containing coconut oil (SFA; n = 10), flaxseed oil (n-3 PUFA; n = 10), or safflower oil (n-6 PUFA; n = 11). Chow-fed rats (n = 10), at 105 days of age, were included to represent animals on a control diet. Rats fed high-fat diets had higher body weights than the chow-fed rats (p < 0.001). Among all high-fat groups, there were no differences in femur BMD (p > 0.05) or biomechanical strength properties (p > 0.05). Femurs of groups fed either the high n-3 or high n-6 PUFA diets were stronger (as measured by peak load) than those of the chow-fed group, after adjustment for significant differences in body weight (p = 0.001). As expected, the femur fatty acid profile reflected the fatty acid composition of the diet consumed. These results suggest that high-fat diets, containing high levels of PUFA in the form of flaxseed or safflower oil, have a positive effect on bone strength when fed to male rats 6 to 15 weeks of age.

scholarly journals Age-dependent effect of high-fructose and high-fat diets on lipid metabolism and lipid accumulation in liver and kidney of rats

2013 ◽  
Vol 12 (1) ◽  
pp. 136 ◽  
Author(s):  
Uberdan Guilherme Mendes de Castro ◽  
Robson Augusto Souza dos Santos ◽  
Marcelo Silva ◽  
Wanderson de Lima ◽  
Maria Campagnole-Santos ◽  
...  
Keyword(s):  
Lipid Metabolism ◽  
Lipid Accumulation ◽  
High Fat ◽  
Dependent Effect ◽  
High Fructose ◽  
High Fat Diets ◽  
Age Dependent ◽  
Liver And Kidney ◽  
Fat Diets

scholarly journals Hepatic Mitochondrial Energetics During Catch-Up Fat With High-Fat Diets Rich in Lard or Safflower Oil

Obesity ◽  
2012 ◽  
Vol 20 (9) ◽  
pp. 1763-1772 ◽  
Author(s):  
Raffaella Crescenzo ◽  
Francesca Bianco ◽  
Italia Falcone ◽  
Sofia Tsalouhidou ◽  
Gayathri Yepuri ◽  
...  
Keyword(s):  
Safflower Oil ◽  
High Fat ◽  
High Fat Diets ◽  
Catch Up ◽  
Fat Diets

Elevated n-3 fatty acids in a high-fat diet attenuate the increase in PDH kinase activity but not PDH activity in human skeletal muscle

2005 ◽  
Vol 98 (1) ◽  
pp. 350-355 ◽  
Author(s):  
Erin A. Turvey ◽  
George J. F. Heigenhauser ◽  
Michelle Parolin ◽  
Sandra J. Peters
Keyword(s):  
Skeletal Muscle ◽  
Fatty Acids ◽  
Pyruvate Dehydrogenase ◽  
High Fat Diet ◽  
Human Skeletal Muscle ◽  
Fat Content ◽  
Pyruvate Dehydrogenase Kinase ◽  
High Fat ◽  
High Fat Diets ◽  
Fat Diets

We tested the hypothesis that a high-fat diet (75% fat; 5% carbohydrates; 20% protein), for which 15% of the fat content was substituted with n-3 fatty acids, would not exhibit the diet-induced increase in pyruvate dehydrogenase kinase (PDK) activity, which is normally observed in human skeletal muscle. The fat content was the same in both the regular high-fat diet (HF) and in the n-3-substituted diet (N3). PDK activity increased after both high-fat diets, but the increase was attenuated after the N3 diet (0.051 ± 0.007 and 0.218 ± 0.047 min−1 for pre- and post-HF, respectively; vs. 0.073 ± 0.016 and 0.133 ± 0.032 min−1 for pre- and post-N3, respectively). However, the active form of pyruvate dehydrogenase (PDHa) activity decreased to a similar extent in both conditions (0.93 ± 0.17 and 0.43 ± 0.09 mmol/kg wet wt pre- and post-HF; vs. 0.87 ± 0.19 and 0.39 ± 0.05 mmol/kg wet wt pre- and post-N3, respectively). This suggested that the difference in PDK activity did not affect PDHa activation in the basal state, and it was regulated by intramitochondrial effectors, primarily muscle pyruvate concentration. Muscle glycogen content was consistent throughout the study, before and after both diet conditions, whereas muscle glucose-6-phosphate, glycerol-3-phosphate, lactate, and pyruvate were decreased after the high-fat diets. Plasma triglycerides decreased after both high-fat diets but decreased to a greater extent after the N3, whereas plasma free fatty acids increased after both diets, but to a lesser extent after the N3. In summary, PDK activity is decreased after a high-fat diet that is rich in n-3 fatty acids, although PDHa activity was unaltered. In addition, our data demonstrated that the hypolipidemic effect of n-3 fatty acids occurs earlier (3 days) than previously reported and is evident even when the diet has 75% of its total energy derived from fat.

scholarly journals Selective Inactivation of Socs3 in SF1 Neurons Improves Glucose Homeostasis without Affecting Body Weight

Endocrinology ◽  
2008 ◽  
Vol 149 (11) ◽  
pp. 5654-5661 ◽  
Author(s):  
Ren Zhang ◽  
Harveen Dhillon ◽  
Huali Yin ◽  
Akihiko Yoshimura ◽  
Bradford B. Lowell ◽  
...  
Keyword(s):  
Body Weight ◽  
Food Intake ◽  
Energy Expenditure ◽  
Glucose Homeostasis ◽  
Leptin Resistance ◽  
High Fat ◽  
Leptin Signaling ◽  
Leptin Sensitivity ◽  
High Fat Diets ◽  
Fat Diets

Suppressor of cytokine signaling 3 (Socs3) has been identified as a mediator of central leptin resistance, but the identity of specific neurons in which Socs3 acts to suppress leptin signaling remains elusive. The ventromedial hypothalamus (VMH) was recently shown to be an important site for leptin action because deleting leptin receptor within VMH neurons causes obesity. To examine the role of VMH Socs3 in leptin resistance and energy homeostasis, we generated mice lacking Socs3 specifically in neurons positive for steroidogenic factor 1 (SF1), which is expressed abundantly in the VMH. These mice had increased phosphorylation of signal transducer and activator of transcription-3 in VMH neurons, suggesting improved leptin signaling, and consistently, food intake and weight-reducing effects of exogenous leptin were enhanced. Furthermore, on either chow or high-fat diets, these mice had reduced food intake. Unexpectedly, energy expenditure was reduced as well. Mice lacking Socs3 in SF1 neurons, despite no change in body weight, had improved glucose homeostasis and were partially protected from hyperglycemia and hyperinsulinemia induced by high-fat diets. These results suggest that Socs3 in SF1 neurons negatively regulates leptin signaling and plays important roles in mediating leptin sensitivity, glucose homeostasis, and energy expenditure.

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